Electrolytic method and apparatus for cleaning strip



June 5, 1951 E. E. VONADA ,556, 7

ELECTROLYTIC METHOD AND APPARATUS FOR CLEANING STRIPS Filed Jan. 29, 1947 2 shqets-snet 1 Flai;

6 1951 E. E. VONADA 2,556,017

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Patented June 5, 1951 ELECTROLYTIC METHOD AND APPARATUS on CLEANING STRIP Edwin E. Vonada, Cleveland, Ohio Application January 29, 1947, Serial No. 725,056

This invention relates to a method and apparatus for cleanin strip and more particularly to cleaning strip in vertical passes. Most of the electrolytic cleaning of metals in strip form is done in horizontal passes which requires a great deal of floor space and an excessive clearance between the electrodes and strip. Vertical cleaning passes have been used to a slight extent, but those in use also have various disadvantages. For example, the electrical hook-up is such that the maximum cleaning action is not obtained at all times. In addition, it is difficult to vary the operation to suit variable conditions.

It is an object of my invention to provide an electrolytic tank and an electrical hook-up therefor which operates uniformly at a high efiiciency.

Another object is to provide a novel method of cleaning strip uniformly and efiiciently.

These and other objects will be more apparent after referring to the following specification and attached. drawings, in which:

Figure 1 is a schematic longitudinal section through the electrolytic tank;

Figure 2 is a view taken on the line 11-11 of Figure 1; and

Figure 3 is an enlarged detail showing the insulated connection between the top of the passageway and the removable electrode.

Referring more particularly to the drawings, the reference numeral 2 indicates a rubber lined electrolytic tank having a chamber 4 in the lower part thereof. The chamber 4 is separated .from the top part of the tank by means of insulation 5 and division plates 8. A rubber covered sink roll ill is positioned in the chamber 4 which has an inlet I2 for the electrolyte. The electrolyte used be any prior art cleaning electrolyte. An insulating barrier Hi extends from the center division plate 8 to a deflector plate it at the top of the tank and divides the top of the tank into two chambers l8 and 2%! which are insulated from each other. A constricted passageway 22 in chamber Isis insulated from the rest of the tank by means ofinsu'lation 24 at the bottom thereof. Fastened to the outside of passageway 22 and to the sides of tank 2 are deflector plates 2%. Within the passage.- Way 22 are removable electrode liners .28 which may be adjusted for movement towardand away from each other in any suitable manner. Insulation 3i separates the liners 28 from the passageway 22. A retricted passageway 32 in chamber 2%} is insulated from the rest of the tank by insulation t l. Deflector plates 36 are fastened to the outside or passageway 32 and to the sides of tank .2. Renewable electrode liners .168 are .adjustably mounted within the 3 Claims. (Cl. 204-.141)

passageway 32 and are separated therefrom by insulation All. An entry conductor roll 42 mounted above chamber [8 and a delivery conductor roll 44 is mounted above the chamber 20. A hood 45 surrounds the rolls 42 and 44 and the top of the tank 2 for collecting the fumes from the cleaning operation. A conduit 48 leads from .the hood 46 to an exhaust fan, not shown. The negative terminal of a generator 50 is connected to the entry conductor roll 42 and its positive terminal is connected to the electrode liners 28. A two-pole double throw knife switch 5! is inserted in the output circuit of generator 50 for reversing the polarity of electrode liners 28[ A second generator 52 has its positive terminal con- .nected to the roll it and its negative terminal connected to the electrode liners 38. A two-pole double knife switch 53, similar to switch 5], is "inserted in the output circuit of generator 5 for reversing the polarity of electrode liners :38.

The strip S enters the tank 2 over the entry conductor roll l? and passes downwardly between the electrode liners as which are so arranged that the clearance between the electrodes and the strip will give the most effective cleaning. The strip then passes under the sink roll I0 then upwardly between the electrode liners 38 and over the exit roll 44. Hold down rolls 5.4 are provided at each conductor roll to insure good contact between the rolls and the strip. Th hold down roll for the exit conductor roll also prevents electrolyte drag out.

As shown in Figure 2, the shaft 56 of the sink roll {0 passes through shaft seals 58 at ,each .end of the tank, the shaft seals being insulated .i-ro-m the tank 2 by meansof insulation. The shaft ,56 is mounted for rotation in bearings 62.

The electrolyte is circulated by means of a pump a l which delivers it from a reservoir 56 to the chamber i through the opening 12. Insulation 6% is provided to prevent grounds and current leakage from the reservoir lifi. The electrolytepasses upwardly through the passageways 2-2 and Stand over the surface of the strip Sat high velocity. The electrolyt solution then flows over'the top of the passageways and leascades downwardly over the plates 25 and .35 which aid in releasing the entrained gases in the electrolyte. Deflector plates It confine the electrolyte within the tank. The electrolyte leaves the tank through conduits it which lead to the reservoir .65. Means for cleaning and conditioning the electrolyte are preferably =10- .cated in the reservoir d6.

With .the generators 5d and 52 connected as shcwnthere are three principal electric circuits. One extends from the positive terminal of the generator 50 to the anodes 28, through the electrolyte solution to the strip S, then to the entry conductor roll 42 and back to the negative terminal of generator 50. The second circuit eX- tends from the positive terminal of generator 52 to the conductor roll 44, then to the stripS, through the electrolyte solution, then to cathodes 38 and back to the negative terminal of generator 52. A third circuit extends from the positive terminal of generator 50 to the anodes 28, through the electrolyte solution to cathodes 38, and then to the negative terminal of generator 52. From here the circuit passes from the positive terminal of generator 52 to the conductor roll 44, through the strip S to the conductor roll 42 and back to the negative terminal of generator 59, thus connecting the two generators in series. Since the electrical current follows the path of least resistance, which path is between the strip and the closely spaced electrodes, the

first two circuits carry substantially all of the current and produce the electrolytic cleaning action. lhe current carried by the third circuit is infinitesimal compared to that of the first two circuits and will not result in any marked heatin of the strip or the electrolyte. Considerableheat is developed in the strip and the electrolyte between the electrodes where the cleaning action is taking place, but this heat is rapidly dissipated by the forced circulation of the electrolyte solution. Since the electrical losses are held to 'a minimum by the complete insulation of the tank and the electrodes and by providing an insulatin barrier between the down and up passes of the strip, the system is very efficient. The rate of liberation of the negative charged oxygen ions is only one-half that of the positive charged hydrogen ions so that maxi-- mum cleaning is obtained by'having maximum hydrogen evolution. However, practical operation requires periodic reversal of electrode polarities in order to reduce the deposit of impurities two generators connected as shown, hydrogen ions will be liberated at the cathodes 38 and oxygen ions at the anodes 28. When it becomes necessary to reverse the polarities of the conductor rolls and electrodes in order to remove impurities built up on the cathodes and prevent undue deterioration of the anodes,the anodes' 28 become the cathodes and the cathodes 38 become the anodes. Thus, one set of cathodes and one set of anodes are present in the tank at all times so that the rate of cleaning always remains substantially the same. Greater flexibility of operation is also obtained by this arrangement. For example, it may be determined at some later stage of the processing that the hydrogen evolved has an injurious effect on the finished product. By simply changing the polarities of both conductor rolls the same rate of cleaning takes place, but an oxygen atmosphere is provided at the delivery end of the tank. The generators 59 and 52 are excited in such a manner that an approximately constant line speed to cleaning current ratio is maintained.

'While one embodiment of my invention has been shown and described, it will be apparent that other adaptations and modifications may be made without departin from the scope of the following claims.

Number I claim:

1. Electrolyte cleaning apparatus comprising a vertical tank, a pair of conductor rolls over which a strip passes into and out of the tank, a'sink roll at the bottom of the tank around which the strip passes, a'pair of electrodes between which the strip passes downwardly in the tank, a second pair of electrodes between which the strip passes upwardly in the tank, means for passing the electrolyte between theelectrodes of each pair of electrodes, a pair of generators for supplying current to the electrodes, means for connecting the positive terminal of one generator to one of the conductor rolls and the negative terminal to the pair of electrodes adjacent thereto, means for connecting the negative terminal of the second generator to the second conductor roll and the positive terminal to the second pair of polarity of the connections between the first generator and its electrodes and conductor roll, and means for reversing the polarity of the connections between the second generator and its electrodes and conductor roll.

2. Electrolytic cleaning apparatus comprising a vertical tank, a pair of conductor rolls over which a strip passes into and out of the tank, a sink roll at the bottom of the tank around which the strip passes, a pair of electrodes between which the strip passes downwardly in the tank, a second pair of electrodes between which the strip passes upwardly in the tank, means for passing the electrolyte between the electrodes of each pair of electrodes, a pair of generators for supplying current to theelectrodes, means for connectin the positive terminal of one generator to one of the conductor rolls and the negative terminal to the pair of electrodes adjacent thereto, means for connecting the negative terminal of the second generator to the second conductor roll and the positive terminal to the second pair of electrodes, means for insulating the pairs of electrodes from each other, an insulating barrier between the up and down passes of the polarity of the connections between the first generator and its electrodes and conductor roll, and means for'reversing the polarity'of the connections between the second generator and its electrodes and conductor roll.

3. The method of continuously cleanin strip electrolytically which comprises passing the strip between a pair of anodic electrodes, passing the strip between a pair of cathodic electrodes, connecting a direct current supply between said strip and said anodic electrodes, connectin a second direct current supply between said strip and said cathodic electrodes, and periodically reversing the polarity of the electrodes.

EDWIN E. VON ADA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED S TATES PATENTS Name Date 943,188 Hartman Dec. 14,1909 1,191,386 Battle July 18, 1916 1,865,470 Hogaboom July 5, 1932 2,264,857 Ranney Dec. 2, 1941 2,317,242 Allen et a1 Apr. 20, 1943 FOREIGN PATENTS Number Country Date 7 133,216 Austria May 10, 1933 60,198 Norway Dec. 19, 1938 

3. THE METHOD OF CONTINUOUSLY CLEANING STRIP ELECTROLYTICALLY WHICH COMPRISES PASSING THE STRIP BETWEEN A PAIR OF ANODIC ELECTRODES, PASSING THE STRIP BETWEEN A PAIR OF CATHODIC ELECTRODES, CONNECTING A DIRECT CURRENT SUPPLY BETWEEN SAID STRIP AND SAID ANODIC ELECTRODES, CONNECTING A SECOND DIRECT CURRENT SUPPLY BETWEEN SAID STRIP AND SAID CATHODIC ELECTRODES, AND PERIODICALLY REVERSING THE POLARITY OF THE ELECTRODES. 